Double salts of nicotine



Patented July 19, 1949 DOUBLE SALTS OF NICOTINE Claude R. Smith,Philadelphia, Pa., assignor to the United States of Americaas'represented by the Secretary of Agriculture No Drawing. Originalapplication September 20,

1941, Serial No. 411,702. Divided and this application July .6, 1944,Serial No. 543,737

(Granted under the act of March 3, 1883 as amended April so, 1928; 3700. G. 757) 4 Claims.

1 This application is made under the act of March 3, 1883, as amended bythe act of April 30, 1928, and the invention herein described andclaimed, if patented, may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment to me of any royalty thereon. This is a division ofmy copending application for patent Serial No. 411,702, filed September20, 1941, now Patent No. 2,356,185.

The primary object of this invention is the production of new doublesalts of nicotine which offer resistance to the often undesirableeffects of moisture, dew, rain, sun, etc., and can be used efiectivelyagainst injurious insects upon vegetation.

Many of these new compounds exert a fumigating effect while in the drydust form superior to any compounds previously known or used. Thisfumigating eifect results from the combinations of nicotine with suchvolatile acids as benzoic, salicylic, etc. In addition to theseadvantages, the compounds containing zinc or copper, both of which arecomponents of fungicides, may supply the necessary fungicidal propertiesin addition to their insecticidal action.

The designation fixed nicotine compound has been customarily applied tosuch weather-resisting materials as the tannate, humate, bentonite,etc., compounds of nicotine. The new compounds of this invention mayalso be so described but they are quite different in type of chemicalcomposition. In comparison with liquid nicotine and nicotine sulphate,the dry dusts represent more convenient physical forms and many of thempossess excellent keeping properties. The natural color of many of thesalts afford an additional safety factor against mistakenidentification.

Important difierences are to be expected in the mode of action of mycompounds as compared to nicotine bentonite, which heretofore has beenconsidered to be the most promising of the fixed nicotine products.Bentonite releases nicotine only by the hydrolysis and volatilization ofthe free nicotine, and when the ratio of bentonite to nicotine increasesthis action is greatly reduced. On dry days, even when hot, very littlenicotine will be released. With a number of my new compoundasuch as thebenzoates and salicylates, the fumigating efi'ect is increased by heatand dryness with simultaneous release of nicotine and the volatile acid.Under moist conditions, a small but definite solubility provides 2nicotine and metal for fungicidal and insecticidal action.

My compounds may be described as coordinated or double salts with themetal probably exerting an auxiliary valency toward the nicotinemolecule. The nature of the acidis an essential requirement. In the caseof most .ordinaryaclds such as boric, oxalic, phosphoric, etc., eitherthey do not serve for double salt formation or no relatively insolublecombinations exist.

The compounds of this invention are limited to the double salts ofnicotine with one of the metals iron, zinc, copper, nickel, cobalt andcadmium. They are further limited in the nature of the acid used to bindthe nicotine and the metal. The acid is selected from a group of acidsconsisting of hydrocyanic, thiocyanic, hydroferrocyanic,hydroferricyanic, chromic, benzoic, salicylic, o-benzoyl benzoic andpicric acids. The acids containing the -C'EN group are highlysusceptible to polymerization and with the metals iron, zinc, copper,nickel, cobalt and cadmium form complex double salts with alkali andalkaline earth metals.

' The acids containing the unsaturated benzene ring including benzoic,o-benzoic, o-benzoyl, picric and salicylic acids are also highlyeffective in double salt formation producing compounds which aregenerally crystalline and often quite insoluble in water. The cadmiumnicotine benzoate, however, is rather soluble and separates only inconcentrated solutions. The double chromates are generally fairlysoluble and must be prepared from concentrated solutions. The zincdouble salt, however, is very insoluble but may be secured in a finelydivided crystalline form. The polymerizing tendency of the chromates isseen in the existence of many polychromates such asthe dichromates, etc.

There are doubtless many derivatives of benzoic acid other than the oneshere employed, such as the 2-4 dichlor, p brom, (their copper salts havebeen prepared), which will form similar double salts. Orthochlorbenzoicacid, however, cannot be used, because the cost of such derivatives,although they may be suitable for double salt formation, would appear tobe. prohibitive of practical application. The metals employed in myinvention are of the coordinating type, probably exerting,:as previouslystated, auxiliary valencies in their complex ion forming com.-

pounds.

Some similar compounds have been heretofore described containingammonia, pyridine, ethylene diamine, etc., but none have been describedcontaining nicotine. Most of my compounds have no corresponding analogsin-anyyotheraorganic base complex salts now known in the art. In thefollowing description when a metal salt or metal is referred togenerally, it is to be understood that one of the metals or salts,designated above is indicated.

Other metals such as titanium;platinumgoldt:'

etc., would serve to producemany ifznotsallzofthe:

corresponding nicotine complex salts but their plete precipitation, butwith the zinc cadmium and iron salts they do not interfere; but mayactually assist the crystallization of. the zinc and cadmiumdouble saltsby. preventing the formation of basic salts of these metals.

The double salts containing ferrocyanide and ierricyanide are probablysuper complex salts costs would be too high for useasinsecticidesandpreparation of my new compounds is: closely -=re.-.

lated to their usual composition as represented.

represents one atom of a metalof the. groupcop; per, zinc, nickel,cobalt, cadmium and iron.. 7 represents a univalent radical such as ahydrocyanic, thiocyanic, pic'ric, benzoic, salicylic, or o-benzoylbenzoic acid radical. The valencyof the metal M is thus represented by nand is 2'with all metals except iron and cobalt where it may be either.2or 3. It is evidentthat the ferrous salts 'maytend to oxidize in the airand can be pre-' pared only by the exclusion of oxygen such as thedouble nicotine ferrous ferrocyanide. The ferrous nicotine doublethiocyanate, however, is a crystalline compound easilyprepared beforeappreciable oxidation results;

With polyvalent acids such as hydroferrocyanic with a valency of, n is-4.,- and' the formula for a bivalentmetal would be For the purpose ofpreparation, one half of the acid is. used to' form the metallic saltand the other half to form the equivalent nicotine salt. The percentageof nicotine may not alwayscorrespond to the general formula althoughapproximated closeiy with the benzoates,

picratesand salicylates; The highly complex nature -of-the doublecyanides,.- ferrocyanides, and ferricyanides prevents an exactformulation of the resul-ting compound.

,In the preparation of new compounds it-should be, understood that: theindividual solutions and thefinal resulting mixture containin -theprecipitated doublesalt should betadjusted to keep Within-the range ofpH 571.5... If; the normal salt isdesiredin the greatest yield it isbestto have all solutions: slightly acid,.arouncl pH 5,. and to make the.final adjustment to pH. 7-7.5. to complete the precipitation. .Excessiveacidity will tend to dissolve and disrupt the compounds. while.excessive alkalinity will formadmixed-basic salts with a loweredcontent. of nicotine. The. resulting com.- pounds of this inventionrepresent essentially combinations of neutral salts. The ferrocyanidecompounds are very insoluble, and colloidal in nature causing difiicultyin filtration; They may be-found particularly ada'ptable tospraymixtures:

In order to spread the action of the dry powders it=may be desirable todilute'them with such materials as tal'c,-starch, kaolin and otherneutral products commonly usedas. diluents for insecticides.

In the preparation of the copper, nickel and cobalt compounds I prefertoavoid the presence ofammonium salts. which :tend to prevent comwhereinthe nicotine salts are conjugated with the metallic ferro andferricyanides. There are ,two generalprocesses employed in thepreparation of my compounds both of which are based on the formulaMXn-mCmfinNa-HX). Process No.1,,.hereinafter described, can be employedwith many but not all of them. It may be employed when the metallic saltcan be first readily prepared and then brought into contact with theequivalent nicotine salt. For example, copper benzoate-can be firstprepared and washed free of soluble salts and brought into contact withthe nicotine benzoate dissolved in water. Copper salicylate, however,-is very soluble and process No. 2 should'be employed. These twoprocesses are as follows:

Process :No. 1.-In-water solution one molecule ofthe metallic salt ofthe metal combined with the acid selected is treated with the equivalentamount of the nicotine saltof the acid. After varying intervals of timethe maximum of the nicotine salt is removed from the solution.- Thefreshly prepared metallic salt while-still wet reacts more rapidly thanafter drying. If the nicotine salt of the acid is not available;equivalent proportions maybe used of a soluble salt of-nicotine with asoluble salt of the acid where the metal may be sodium,- potassium,ammonium; calcium, magnesium or other non-coordinating metal.

Process N0. 2.This'process is generally applicable to all compounds andconsists in-bringing together a soluble salt of the metal with theequivalent quantity of a soluble salt of the acid such as thesodiunnpotassium, ammonium, calcium magnesium or other non-coordinatingmetal salt and the equivalent quantity of the nicotine salt of the acid.If the nicotine salt'is not available it is only necessary to use anequivalent amountof some nicotine salt with an equivalent of the solublesalt of the acid such as the sodium, potassium, ammonium, calcium,magnesium or other non-coordinating metal. The double salt obtained willcontain only the acid selected from the group of polymerizing acids ofthis invention and, if desired-, may be washed free of contaminatingsoluble salts.

' The following examples illustrate in more detailthe manner ofpreparing the new; compounds ofmy invention- Example 1 Onemolr of copperacetate is added to a mixture of 2 mols of sodium benzoate and :2 'mols'of nicotine benzoate allin water solution. If'normal solutions of thesethree compounds. are used the precipitated copper nicotine compoundforms a rather dense mixture.-- I pref-er; thereforandie lutionwith more.watenbefore filtration is made. Arslight excess of dissolvedbenzoicaciduwill Produce a mixture between.pH.5 and-pI-I,-'.7.. The pHmay be adjusted .to .7-7 .5 withdilutemicotine alkaloid solution inwater to secure maximum precipitation yet avoid the production of basic(C. R. S.) salts. The washed and dried copper nicotine benzoate analyzes7.7% for copper. and 37% to 38% fornicotine;-theoryfor Cu is-'l-.2'T%and for nicotine 3751 Example 2 One mol of copper sulphate is added to amixture of 2 mols of sodium thiocyanate and 2 mols of an equivalentnicotine thiocyanate produced by a mixture of 2 mols of nicotinehydrochloride and 2 mols of sodium thiocyanate. Cupric nic otinethiocyanate is produced as a bright green colored product quiteinsoluble in water. On boiling with alkalies, cupric oxide is formed.

Example 3 Copper acetate in aqueous solution is added to a mixture of 2mols of sodium cyanide and 1 mol of a neutral nicotine salt until aslight excess of copper is present. The salt to be expected,corresponding to the formula expected Cu (CN) 2 ZCiuHMNzI-ICN losescyanogen, and a brown insoluble salt analyzing as nicotine cuprouscyanide is produced.

Example 4 Two mols of copper acetate is added to a mixture of 2 mols ofa ferrocyanide salt and 4 mols of nicotine hydrochloride. The doubleferrocyanide has a bluish red color, filters well, although thegelatinous product dries slowly.

Example 5 Two mols of zinc acetate may be used instead of the copperacetate in Example 4. The resulting product is yellowishwhite, highlycolloidal, and filters slowly.

Example 6 Instead of copper sulphate in Example 2, nickel acetate may beused to obtain a crystalline blue double thiocyanate.

Example 7 Instead of copper sulphate in Example 2, cobalt acetate may beused to obtain a crystalline pink double salt.

Example 8 Instead of copper sulphate in Example 2, cadmium acetate maybe used to obtain a crystalline white double salt.

Example 9 One mol of ferric chloride and a mixture of 6 mols of sodiumthiocyanate and 3 mols of nicotine monohydrochloride results in a doublesalt that is bluish red to red in color but turns brownish on prolongedwashing, probably due to hydrolysis.

Example 10 One mol of ferrous ammonium sulphate dissolved in water andadded to a mixture of 4 mols of sodium thiocyanate and 2 mols ofnicotine monohydrochloride results in the precipitation of a double saltthat is a brownish white crystalline product.

Example 11 To a mixture of two mols of potassium ferrocyanide and 4 molsof nicotine hydrochloride a solution of ferric ammonium sulphate isadded containing one molecular equivalent of Fe. The resulting bluedouble salt is quite insoluble and filters with some difiiculty, leavinga gelatinous product.

Example 12 If instead of copper acetate in Example 4 nickel acetate isused, a greenish blue double salt of nickel nicotine ferrocyanide isproduced.

Example 13 (CaSOa 2H20) is nonhygroscopic and need not be Washed out ofthe material when the resulting nicotine double salt is to be employedas an insecticide in dust form.

Having thus described my invention, I claim:

1. An insecticidal and fungicidal agent comprising a nicotine complexsalt of the formula MXn'7'L(C10H14N2'HX) in which M is a polyvalent Ycoordinating metal taken from the group consisting of copper, zinc,nickel, cadmium, iron, and cobalt; n is 2 or 3; and X is a radical ofthe group consisting of CN and CNS, both X's being identical; n beingthe valence of the metal M.

2. The agent of claim 1 in which the acid radical is CN.

3. The agent of claim 1 in which the acid radical is CNS.

4. An insecticidal and fungicidal agent comprising the cupric nicotinethiocyanate of the formula Cu(CNS) 22(C10H14N2 -HCNS) CLAUDE B. SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,750,160 Davis Mar. 11, 1930FOREIGN PATENTS Number Country Date 77,437 Germany Oct. 4, 1894 147,999Switzerland Sept. 16, 1931 492,660 Great Britain Sept. 20, 1938 OTHERREFERENCES Chem. Abstracts, vol. 33, page 1870 (1939) (citing BritishPatent 492,660).

1Pictet et al.: Vegetable Alkaloids, page 943).

